There is a fundamental gap in understanding of the functional and structural reorganization of the brain that takes place as a result of therapeutic interventions. Continued existence of this gap represents an important problem in mental health research because, until it is filled, design of more effective and efficient interventions will remin largely unguided. Our long-term goal is to use non-invasive detection and monitoring of brain reorganization to guide the development and implementation of therapies. The objective in this particular application is to develop a reliable and sensitive MR imaging indicator of brain network plasticity and apply it to study the remodeling of structural brain networks in children with cognitive training. The rationale for the proposed network approach is that brain changes resulting from therapies are not confined to a specific brain region but usually involve communication pathways and this is directly addressed by diffusion MRI connectomics that treats the brain as a network of structural connections between brain regions. The central hypothesis is that diffusion MRI-based brain networks and their graph-analytic properties can serve as a reliable and sensitive indicator of plasticity in children with cognitive training. We wll study brain network changes in 10-18 year-old youths who undergo a 12-week mindfulness meditation-based training of attention and emotion regulation and correlate the results with the behavioral changes according to the computer-based Attention Network Test (ANT). The proposed research is significant, because it is expected to provide a method for monitoring the efficacy of therapeutic interventions, guide the development of new interventions, and advance our understanding of how the brain reorganizes as a function of intensive practice of specific cognitive functions. Ultimately, such knowledge has the potential to inform the development of treatment for clinical populations, such as children and adolescents with attention deficit hyperactivity disorder (ADHD), depression and anxiety disorders.